[63 Pontiac]

So my 68 Cat 2 door sedan failed inspection due to rust thru in the frame. The inspection tech showed me the problems areas while the car was on the lift and the rust is fixable but it would only be a short-term fix. This car is a keeper so it's time for a frame swap. Do I need a 2 door Catalina frame only or will the 4 door frame work also?

[incommunicado]

i dont know if it will work, but I have a bare 67 GP boxed frame for free.

I also have a rolling 67 GP coupe parts car for $200 with a good frame.

[63 Pontiac]

incommunicado, PM sent.

Alright, can anybody confirm that 67 GP frame will work with a 68 Catalina 2 door sedan body?

[A390GT]

I think the 67 gp is the same wheelbase but a tad shorter... it’s been some time since I had that car. It was very close to my 68 hardtop in length it was an inch or so.shorter.

you’ll Just have to measure trunk body mount positions and see if they line up
I think body mounts from the rear foward in the 2 doors cars are the same

I have a 68 gp parts car with a good frame. ( n.j.)
But, The 68 gp is a tad shorter than a 68 coupe, so you’ll probably have the same problem

John-

[north]

I would think that all the non wagon frames that had a 121" wheelbase would interchange. Convertible frames were boxed but they were offered on other models as a HD frame. 4 door hardtop frames were a bit stronger (not boxed like ragtops but a bit stiffer than the basic frame but again interchangeable). I would also suspect that any 65-68 would also interchange

I'll double check in my MPC tonight.

[north]

The factory part numbers are all over the place. I saw that Franks in California has a bunch of full size frames and he has a lot of hands on experience with interchangeablity.

As previously mentioned I’d watch out for the GP in case the unique quarters resulted in a relocation of the rearmost body mount as compared to the Catalina.

[63 Pontiac]

Thanks for all info, my first inclination was that the Catalina wheelbase frames would all be the same but that must not be the case. I'll check with Frank's and go from there.

[perryka]

Maybe this will help.

From my 67 service manual, it states that the convertible, hardtop, 124" wheelbase sedan, station wagon and Grand Prix frames are essentially the same as other corresponding wheelbase frames but have the center side rail fully boxed for additional stiffness.

From looking at the charts: All Catalina models, as well as all station wagons, have 121" wheelbase frames. Executive and Bonneville models (except wagons) have 124" wheelbase frames.

Both Catalina hardtop models (2 dr and 4 dr) and the Grand Prix hardtop have all frame dimensions exactly the same. The only variance between the Cat hardtop and sedan frames is a difference of .04" at the outside of the front frame rails, at the very front, and .04" outside to outside at the rear of the frame at the rear cross member. The sedans are narrower at those points. All other sedan dimensions are identical to the hardtops and the Grand Prix hardtop.

Except for the obvious differences in the different wheelbase model dimensions, when you look through the chart the biggest variation in some of the measurements is .05" in a couple places. So we're not talking about a lot of variation.

All the frames have the same holes within each wheelbase frame. If you look at the frame mount chart, the only difference among the models is the color and configuration of the insulator used at each of the mounting points. The one difference is the wagons, which use a different set of holes midway between the two rear cross members than the other 121" models.

Regardless of the small differences in overall outside body dimensions between some of the variations within and between the models, it appears there is great commonality within the frames.

I don't have my 68 manual any more because it went with my wagon when I sold it, but I would think that the characteristics would be the same across the 68 models as they are for 67, since they share so much commonality.

Now, what is the commonality and interchange BETWEEN 67 and 68? Can't say for sure since I can't compare manuals at the moment, but I would be real surprised if the frames were real different, given how much else is common between the two years.

Interested to see what you learn from Frank.

Alan

[63 Pontiac]

Alright, here's a quote from Frank's Pontiac:

"Catalina 2dr & 4dr sedan use the same frame, the 2dr & 4dr Ht frame will also work but it is heavier duty."

Did not ask think to ask about the '67 interchange, may have to follow up on that.

[63 Pontiac]

Thank you for the information, Alan, and to everyone else as well. After some emails with Frank I don't know what the interchange is exactly. Regarding the GP frame the difference may be in the frame horns. Not sure if the bumper mounts differently between the GP and Catalina? If that's all it is then it should be an easy modification to mount a Catalina bumper to the GP frame.

[incommunicado]

its free if you want it and we can load it with a forklift.